JP2601884B2 - Reactor protection equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Purpose of the Invention] (Industrial application field) The present invention prevents a secondary disaster of a nuclear power plant by emergency insertion of a control rod when a reactor operation is abnormal. It relates to a reactor protection device.

(Prior art) A reactor protection device for a nuclear power plant is a device for suppressing the reactivity of a reactor by urgently inserting a control rod in the event of an abnormality such as an accident in which the operation of the reactor must be stopped. .
For this reason, it is required that the operation of the reactor protection apparatus be surely operated by detecting abnormal signals from various sensors. On the other hand, it is not preferable in operation that power generation is stopped due to malfunction of the reactor protection device. Therefore, the device for inserting the sensor and the control rod is designed to have high reliability in consideration of redundancy.

FIG. 3 is a configuration diagram of a conventional reactor protection apparatus. A reactor core 2 is provided inside a reactor pressure vessel 1 and is filled with light water 3. The core 2 mainly includes fuel rods (not shown) and control rods 4A to 4N. For example, in a 1 MW class nuclear reactor, about 200 control rods are provided, and each control rod penetrates the reactor pressure vessel 1 and has a hydraulic control rod drive mechanism 5A to 5A.
It is driven by 5N.

The operation of one of the approximately 200 control rod drive mechanisms 5A to 5N will be described as an example. In the case of a boiling water reactor, the control rod drive mechanism 5A is a kind of piston structure using water pressure. Thus, the extraction pipe 6A and the insertion pipe 7A are connected to this. The pipes 6A and 7A are connected to a directional control valve unit 8A, an outlet scrum valve 9A and an inlet scrum valve 10A, respectively. The control rod drive mechanism 5A pulls out the control rod 4A from the reactor core 2 when drive water flows in from the pull-out pipe 6A, and increases the reactor power. Conversely, when drive water flows in from the insertion pipe 7A, the control rod
4A is inserted into the core 2 to lower the reactor power. The opening degree of the outlet scram valve 9A and the inlet scram valve 10A is controlled by air pressure, and the pneumatic pressure is controlled by the backup scrum pilot valves B and 13B as well as the scrum pilot valve 12A and the backup scrum pilot valves A and 13A through the scram valve air pipe 11A. Is controlling. During the power operation of the nuclear reactor, air pressure is applied from the air supply source 14, and the outlet scram valve 9A and the inlet scram valve 10A are closed. The scram pilot valve 12A has the same structure as the solenoid valve solenoids A and 15A, except that the solenoid valve solenoids B and 16A are electrically excited. In addition, the backup scrum pilot valves A and 13A and the backup scrum pilot valves B and 13B
When the solenoid valves C and 17A and the solenoid valves D and 17B are electrically de-energized, the air supply source 14 supplies compressed air.

The solenoid valves A and 15A are excited by logic circuits A and 18A and the solenoid valves B and 16A are excited by output signals of logic circuits B and 18B, respectively. If there is an abnormality in the reactor, the output signals of the logic circuits A and 18A and the logic circuits B and 18B disappear, and the opening direction of the scram pilot valve 12A is switched. This allows
The air in the scram valve air pipe 11A is exhausted through the exhaust pipe 23A, and the outlet scram valve 9A and the inlet scrum valve 10A that have been closed are opened. When the two scrum valves 9A and 10A are opened, high-pressure drive water flows from the control rod drive water filling device 19A through the insertion pipe 7A and into the control rod drive mechanism 5A. At this time, the driving water above the control rod driving mechanism 5A is discharged to the driving water drainage container 20A through the drawing pipe 6A and the open outlet scrum valve 9A. As a result, the control rod 4A is rapidly inserted into the core 2.

Here, backup scram pilot valves A and 13A and backup scram pilot valves B and 13B of the reactor protection device will be described as devices for rapidly inserting the control rod 4A similarly to the scram pilot valve 12A. Backup scrum pilot valves 13A, 13B
Is a configuration in which two valves are connected in series upstream of an air pipe in which the scrum valve air pipes 11A to 11N of the scrum pilot valves 12A to 12N merge into one. The backup scrum pilot valves 13A and 13B are
When the reactor core 2 is in the output operation as in the case of 12A to 12N, the valves are opened in the direction of passing the pressure air from the air supply source 14, and the respective solenoid valve solenoids A and 13A and the solenoid valve solenoids B and 13B
Is non-excited. Therefore, when there is an output signal from the reactor protection device, if any of the backup scram pilot valves 13A and 13B is excited, the control rods 4A to 4N can be rapidly inserted into the core 2 so that the piping configuration is N. This is a retrofitting device in consideration of the case where even one scrum pilot valve did not operate. The solenoid valves C and 17A and the solenoid valves D and 17B of the backup scrum pilot valves A and 13A and the backup scrum pilot valves B and 13B are provided when the logic circuits A and 18A and the logic circuits B and 18B are simultaneously established. That is, the logic circuit A & B 21 is established and the opening direction of the backup scrum pilot valves 13A and 13B is switched to exhaust the air in the scram valve air pipes 11A to 11N from the exhaust pipes 23'A and 23'B, and the aforementioned scrum pilot The control rods 4A to 4N are rapidly inserted into the core 2 as in the description of the valve.

Next, the logic circuit of the reactor protection device will be described with reference to the circuit configuration diagram of FIG. Logic circuits A and 18A comprise trip logic A1 channel 24 and trip logic A2 channel 25.
When the AND circuit is established, the solenoid valves A and 15A of the scrum pilot valve 12A are excited. Logic circuits B and 18B are trip logic B1 channel 2
When the AND circuit is established, the solenoid valves B and 16A of the scrum pilot valve 12A are excited. Each channel of the trip logic is a circuit for inputting parameters such as a reactor pressure, a reactor water level, and a core neutron flux, and detects an abnormality of the reactor. If these parameters are sound, the logic circuits A and 18A and the logic circuits B and 18B are established,
Output signals are sent to the solenoid valve solenoids A and 15A and the solenoid valve solenoids B and 16A, respectively. In addition, the logic circuits A and 18A and the logic circuits B and 18B are respectively AND circuits of the NOT signals, and the logic circuits A and B are connected to the backup scrum pilot valves 13A and 13B.
21 is a solenoid valve solenoid A for the scrum pilot valve 12A, 1
5A and solenoid valve solenoids B and 16A do not output any signal.

That is, during the reactor power operation, the solenoid valves C and 17A and the solenoid valves D and 17B of the backup scram pilot valves B and 13B as well as the backup scram pilot valves A and 13A are demagnetized. Therefore, if there is no abnormality in the reactor during the reactor power operation, the solenoid valves A and 15A and the solenoid valves B and 16A are excited, and the solenoid valves C and 17A and the solenoid valves D and 17B are demagnetized. On the other hand, if there is an abnormality in the reactor, the operation is reversed. FIG. 4 shows only the ethics circuit of the reactor protection device which operates automatically, and the manual logic circuit is omitted.

(Problems to be Solved by the Invention) In the conventional reactor protection device, the scram pilot valve 12
Even if A and the backup scrum pilot valves 13A, 13B are sound, the logic circuits 18A, 1
If 8B or logic circuit power supply failure, etc.
It is conceivable that 4A to 4N cannot be inserted urgently. These phenomena, although probabilistically low, can lead to nuclear power plant accidents when they occur,
There was a demand for measures to improve safety.

The present invention has been made in view of the above, and an object of the present invention is to provide a logic circuit of a reactor protection device and a protection device independent of a power supply and the like of the logic circuit to reduce a risk of an accident at a nuclear power plant. It is an object of the present invention to provide a reactor protection device that reduces the number of reactors and enhances the reliability and safety of operation.

[Configuration of the invention]

(Means for Solving the Problems) In the conventional reactor protection device for emergency insertion of a control rod, a logic circuit, a power supply, and a logic circuit for receiving an abnormal reactor signal and generating an emergency insertion signal of the control rod are provided. Provide a protection device consisting of a three-way valve.

(Operation) Even if the conventional reactor protection device does not operate due to a failure or the like,
In response to an abnormal signal from the reactor via an independent logic circuit using a separate power supply, the outlet scram valve and the inlet scram valve that directly control the control rod drive mechanism are operated to completely insert control rods, thereby suppressing reactor power output. Do

Example An example of the present invention will be described with reference to the drawings. In addition,
The same reference numerals are given to the same components as those of the above-described conventional art, and the detailed description is omitted. FIG. 1 is a configuration diagram, in which the reactor body and the drive control devices for the control rods 4A to 4N are the same as those in FIG. Therefore, in FIG. 1, the backup scrum pilot valves B and 3B and the air supply
And a protection device 30 is provided between them. The protection device 30 controls the solenoid valves 34A and 34B of the three-way valves A and B 31A and 31B, the check valve 32 and the air pipe 33, and the solenoid valves 34A and 34B of the three-way valves A and B 31A and 31B. ATWS logic circuit 35
It consists of A and 35B.

The ATWS logic circuits A and 35A are constituted by an OR circuit of the reactor pressure high A signal 36A and the reactor pressure signal 36C and the reactor water level low A signal 37A and the reactor C signal 37C as shown in the circuit diagram of FIG. When this OR circuit is established, the solenoid valves E and 34A of the three-way valves A and 31A are excited. ATWS logic circuit B, 35B
Is composed of an OR circuit of the reactor pressure high B signal 36B and the reactor D signal 36D and the reactor water level low B signal 37B and the reactor D signal 37D. The three-way valves A and 31A and the three-way valves B and 31B are the same three-way valves as the backup scrum pilot valves 13A and 13B described above.

 Next, the operation of the above configuration will be described.

The three-way valves A and 31A and the three-way valves B and 31B are operated when there is no output signal from the ATWS logic circuits A and 35A and the ATWS logic circuits B and 35B, that is, when the reactor is in output operation and an abnormality occurs in the reactor. If not, the solenoid valve solenoids E and 34A and the solenoid valve solenoids F and 34B are demagnetized. In this state, the air supply 14
Pressure air passes through the exhaust side of the three-way valves A and 31A, flows into the backup scrum pilot valves B and 13B, and the scram pilot valve 12A and the scram valve air pipe 1
After 1A, the outlet scrum valve 9A and the inlet scrum valve 10A are closed. In this state, the control rod 4A remains stationary in the pull-out direction.

If an abnormality occurs in the reactor, the ATWS logic circuits A and 35A and the ATWS logic circuits B and 35B simultaneously output signals according to the reactor pressure high signals 36A to 36D and the reactor water level low signals 37A to 37D that are generated at that time. , Each solenoid valve solenoid E, 34A
And the solenoid valves F and 34B are excited, and the opening direction of the three-way valve is switched.
When the OR circuit is established, the solenoid valves F and 34B of the three-way valves B and 31B are excited. The solenoids 34A and 3A of the three-way valves A and 31A and the three-way valves B and 31B are excited.
By the excitation of 4B, the opening directions of the three-way valve are both switched, the flow path of the pressure air flowing from the air supply source 14 is cut off, and the air in the scrum valve air pipes 11A to 11N is exhausted from the exhaust pipe 23 ″. Each signal of ATWS logic circuit 35A, 35B separates the logic circuit of the conventional reactor protection device, the detection instrument, the logic power supply, etc. as a separate circuit, and the circuit operates without any effect even when multiple failures occur in the conventional device There is.

When the compressed air is exhausted from the exhaust pipe 23 ″, as a result, the outlet scram valve 9A and the inlet scram valve 10A open, and the high-pressure drive water from the control rod drive water filling water 19A passes through the insertion pipe 7A, and the control rod drive Control rod 4A to flow into mechanisms 5A to 5N
-4N are rapidly inserted into the reactor core 2 to reduce the reactor power. At this time, the three-way valves A and 31A and the three-way valves B and 31B are not connected to the control rod 4A unless the opening directions of the valves are simultaneously switched.
Because it is a pipe connection that can not insert up to 4N, accidental shutdown of the reactor does not occur due to malfunction of only one of them. For example, if the three-way valves A and 31A malfunction, if the solenoid valves E and
A is excited from the erroneous signal, the opening direction of the three-way valve is switched, and the compressed air from the air supply source 14 is closed.
If B is normal, the pressurized air can pass through the three-way valves B and 31B to keep the outlet scram valve 9A and the inlet scrum valve 10A pressurized.

The protection device 30 includes backup scrum pilot valves A and 13A and backup scrum pilot valves B and 1
An air pipe 33 bypassing 3B and a check valve 32 are provided.
This is the case when only the protection device 30 is activated.
The backup scram pilot valves A and 13A or the backup scram pilot valves B and 13B are closed due to the rapid flow of the compressed air exhausted from the 23 ″ due to the structure of the valves. Therefore, in the conventional protection device, it is conceivable that the protection device does not operate due to multiple failures, and such an event is low in probability, but is supposed to occur. If so, it is conceivable that a failure that cannot be dealt with by the judgment and operation of the operator may occur, but in the present invention, the above probability can be further reduced,
Reactor pressure and reactor water level are adopted as parameters for detecting control rod insertion failure, and all control rods are automatically inserted to maintain the integrity of the reactor. In addition, due to the configuration of the installed three-way valve and the air pipe, careless insertion of the control rod can be avoided even in the event of a one-way malfunction of the three-way valve.

〔The invention's effect〕

According to the present invention, when an abnormality occurs during the operation of a nuclear reactor in a nuclear power plant or the like, even if the conventional protective device fails, even if the conventional protective device malfunctions, the emergency injection of all control rods is performed by a separate protective circuit. The overall reliability is extremely high, and the effect is that the operation efficiency and reliability of the nuclear power plant are greatly improved while the equipment is simple.

[Brief description of the drawings]

FIG. 1 is a block diagram of one embodiment of the present invention, FIG. 2 is a circuit block diagram of a logic circuit of the present invention, FIG. 3 is a block diagram of a conventional reactor protection device, and FIG. 4 is a conventional logic circuit. FIG. 3 is a circuit configuration diagram of FIG. 4A to 4N: Control rod, 5A to 5N: Control rod drive mechanism, 6A: Pull-out piping, 7A: Insertion piping, 8A: Directional control valve unit, 9A: Outlet scram valve, 10A: Inlet scram Valves, 11A to 11N: Scrum valve air piping, 12A: Scrum pilot valve, 13A, 13B ... Backup scrum pilot valve, 14: Air supply source, 15A: Solenoid valve solenoid A, 16A: Solenoid valve solenoid B, 17A ... Solenoid valve solenoid C, 17B ... Solenoid valve solenoid D, 18A, 18B, 21 ... Logic circuit, 19A ... Control rod drive water filling device, 22, 32 ... Check valve, 23A, 23 'A, 23'B, 23 "... Exhaust pipe, 30 ... Protector, 31A, 31B ... Three-way valve, 33 ... Pneumatic piping, 34A ... Solenoid solenoid E, 34B ... Solenoid solenoid F, 35A, 35B ... ATWS logic circuit.

Claims (1)

(57) [Claims] An air pipe for supplying pressure air to a scram valve for controlling driving water supplied to a control rod drive mechanism for urgently inserting a control rod of a nuclear reactor such as a nuclear power plant, and an air pipe for supplying pressure air to the scram valve. A reactor having a scram pilot valve to be controlled, a backup scram pilot valve and a check valve arranged in parallel on the upstream side thereof, another backup scram pilot valve arranged in series on the upstream side thereof, and a pressure air supply source provided upstream thereof. In the protection device, another check valve provided in a pipe communicating between the upstream side of the other backup scrum pilot valve in series and the downstream side where the backup scrum pilot valve merges with the check valve. A pipe connected in series between the upstream side of the other check valve, the upstream side joined with the other backup valve and the pressure air supply source, A three-way valve is provided, and an independent protection device comprising a logic circuit for operating the solenoid valve solenoid with a separate power supply when a plurality of reactor abnormal signals are input to the solenoids for driving the respective three-way valves. A nuclear reactor protection device characterized by comprising: